Originally Posted by cyccommute

You aren’t saying anything that I haven’t already said. If the brake is tight enough it shouldn’t move. If it can be moved by hand without tools, it’s not tight enough and won’t stay centered. Vibration will move it off-center or even pulling the cable will torque the brake to one side. Again, Shimano says 8 to 10 Nm of torque to hold it in place. 6 Nm is what I have currently use...set by a Park Tool ATC-1.2 torque wrench...and I can’t move it off center by hand.